Backlash is a linear distance between two gears in mesh and is measured perpendicular to a gear tooth at a pitch diameter of one of the meshed gears. Measurement systems for measuring backlash may be constructed for use in open spaces and where it is not difficult to plant testing equipment in such open spaces. However, in some situations, measuring backlash in a gear may be difficult when the gear is located in closed or confined spaces, such as a ring gear disposed within a housing of an engine. Further, conventional measurement systems constructed for use in such applications may be bulky, cumbersome, and difficult to handle while taking measurements of backlash accurately.
JP Published Application 2006-317310 relates to an inspecting apparatus equipped with a driving mechanism for rotating a crankshaft, and an engagement adjusting mechanism for adjusting the engagement state of the crank gear and a balancer gear. The engagement adjusting mechanism adjusts them alternatively in directions being a driven direction in which rotation is performed by the crank gear, and its reverse-driven direction. The inspecting apparatus further comprises rotation angle detecting means which detect rotation angles of shafts respectively, and a thrust displacement measuring means which detects a movement of a balancer shaft in the axial direction. The engagement state of the crank gear and the balancer gear is adjusted during a period of prescribed rotation number in the driven direction, and then the direction is changed into the reverse-driven direction, and a backlash between the crank gear and the balancer gear is calculated based on displacement values measured by respective rotational angle detecting means and the thrust displacement measuring means.